Although fall has only just begun, it is not too early to start thinking about winter, especially since this one may look very different from previous years due to El Nio.
The effects of the phenomenon, which has a significant impact on the weather during the coldest months of the year, will be felt for the first time in a few years this winter.
El Nio is one of three phases of the El Nio Southern Oscillation, which tracks changes in water temperature in the equatorial Pacific Ocean that can have a global impact on weather patterns. El Nio occurs when ocean temperatures are warmer than normal for an extended period of time.
According to NOAA’s Climate Prediction Center, this year’s El Nio began in June and is expected to be strong this winter and last at least until early next spring.
La Nia, El Nio’s cooler counterpart, has played a significant role in the past three winters across the United States, keeping the South dry while providing much-needed snow to parts of the West.
The Climate Prediction Center’s early winter predictions bear many of the hallmarks of typical El Nio winters, portending future changes.
How might this winter look?
No two El Nio winters are alike, but many share temperature and precipitation trends.
The position of the jet stream, which frequently shifts south during an El Nio winter, is one of the major reasons. According to NOAA, this shift typically brings wetter and cooler weather to the South while making the North drier and warmer.
Because the jet stream is essentially a river of air through which storms flow, they can move across the South more frequently during an El Nio winter. More storms mean more rain, which usually falls from the southern Plains to the Southeast. This could be critical for drought-stricken states like Texas, Louisiana, and Mississippi.
The combination of cooler temperatures and more frequent precipitation may increase the likelihood of wintry precipitation such as freezing rain, sleet, and snow falling in the South.
El Nio is known to cause milder winters in the North, from the Pacific Northwest to the Rockies, Plains, and Midwest. Individual storms can still form and bring brutal cold or heavy snow to these areas, but they are less common.
This would be bad news for parts of the Midwest that are also experiencing extreme and exceptional drought, as well as for snowpack in the Pacific Northwest, which is a critical water source for the region.
Winter El Nio patterns are less consistent in California, the Southwest, and the Northeast.
The frequency of storms and increase in precipitation across California and parts of the Southwest may be affected by El Nio’s overall strength. A stronger El Nio may bring more storms, low elevation rain, and high elevation snow, whereas a weaker version may leave the Southwest hanging.
During an El Nio winter, the Northeast does not have a well-defined set of expectations. The region may be milder overall than its northern counterparts, but it is also vulnerable to powerful coastal storms moving along the Atlantic Coast.
Looking back at recent El Nio winters can also help predict what the upcoming winter will bring:
- Several notable storms occurred during the 2018-2019 season due to a weak El Nio, including one in December that brought snow and ice from Texas to the Carolinas. According to NOAA, the season was also the wettest winter on record for the US mainland, with above-average temperatures across much of the East.
- According to NOAA, a very strong El Nio during the 2015-2016 winter contributed to the warmest winter on record for the US mainland. Massive snowstorms, including a deadly blizzard that halted East Coast travel, were unaffected by the mild winter.
- The winter of 2009-2010 was the last with an El Nio of the strength predicted for this year. According to NOAA data, it was quite cold across the southern and central United States, and very wet and snowy along the East Coast. Multiple blizzards slammed the Northeast in quick succession during the season.